Digital BW, The Print

Ernst,

With a wood-pulp paper base, even if the lignin has been mostly removed --
and maybe even with a cotton base -- some buffering is needed to stop acids
from being formed, at least at some level, even if due to atmospheric gases
attacking the cellulose.  So, mere deacidification by Epson would not solve
the problem.  The paper would probably be acidic again by the time we used
it.

(Acids apparently build up quickly in sealed enclosures.  Old books that are
sealed can deteriorate at 10 times the rate of those that can "breath" and
release some of the H+ ions to the air.  Some of the materials I've read on
the subject call the reactions "auto-catalytic," snowballing at ever faster
rates.  Of course, EAM is sealed until we open the containers.)

More interesting than why Epson doesn't deacidify the paper is why there is
no calcium carbonate in the paper base.  That too is cheap.  My assumption
is that there is some negative affect on the image -- either dMax or image
stability.  If this is so, then even if they just put the buffer on the back
(like with a Bookkeeper application), it would be transferred to the front
by contact, since the paper is stored front-to-back.

I noted previously that the deacidified EAM prints the same as the standard
EAM.  I now have a control, untreated EAM and a deacidified, back-buffered
EAM in the fader and we'll see what happens.  I hope that the application of
the buffer on the back avoids any negative effects it might have on the
image.  My reading suggests that, while the acids' damaging H+ ions migrate,
the buffers do not.  So the magnesium oxide buffer should be well isolated
from the image -- as long as the prints are not stacked.

Paul
_________________________

>> 15 minutes in a bag/zip lock with ammonia is all that
>>is needed to deacidify
>> EAM (meaning the Abbey pH test pen shows good purple - pH
>>higher than 6.8 - even on interior fibers).
>>Of course, no buffer is introduced with just the
>> ammonia treatment.  Bookkeeper spray to the back is
>>probably the best we can do for buffering future acid production.

>And they can't do that for us at the Epson paper plant ?
>Very cheap process so price can not be the reason.